But the aspect that boomed out most loudly was his relentless pursuit of secular humanism in the face of ignorant religion. That came across even when his last doctor, Francis Collins, was speaking, addressing the memorial audience as a “follower of Jesus Christ”.

Collins, head of the US National Institutes of Health, said Hitchens had helped forward the search for scientific answers to cancer by agreeing to try new therapies. Collins also revealed that, ironically, he had prayed for the great atheist in his final days.

Even Hitchens – ever the auto-contrarian – had a poke at himself in that regard, too. At the end of the Gibney film Hitchens – his head by now bald from chemotherapy-induced hair loss – is heard insisting that there is no after life.

“I will never change my mind on that. Never change my mind,” he says.

After a pause, he adds: “But I do like surprises.”